The present invention relates to the management of physical data storage resources in Storage Area Networks (SAN) consisting of an array of host computers and an array of storage devices coupled in a storage network by a Network Switch. All I/O operations of each host out of the array of hosts of the SAN are processed centrally by the Network Switch for routing to the array of storage devices. In addition, since the Network Switch also centrally manages memory storage allocation, running both tasks of routing I/O operations and managing storage allocation often create bottlenecks preventing timely operation of the SAN.
Storage systems may be related to as pertaining to distinct generations. A first generation of storage system dealt with a single host having a file system that communicated directly with a single storage device. For example, U.S. Pat. No. 5,983,316 disclosed by Norwood, divulges a first generation implementation of virtualization for a single host and a plurality of storage devices. U.S. Pat. No. 5,404,478 divulged by Arai et al., also describes virtualization and its implementation for a multiplicity of host and storage device pairs, thus again for a one to one relation of the first generation of storage virtualization. The second generation of storage systems consisted of a host with a single operating system able to handle RAIDs (Redundant Array of Independent Disks), which may include multiple and various physical devices such as Disks, JBODs (Just a Bunch of Disks), Tapes and so on.
In the third novel generation of storage systems, disclosed below, an abstraction of the RAID is introduced, for an array of hosts with an operation system to communicate with Virtual Volumes. The Virtual Volumes are presented to the hosts as a logical representation of the storage devices, instead of setting the hosts in direct communication with the physical storage. This third generation of storage system belongs to the present invention, as described below.